Electronic throttle controls or “ETCs” are well known for controlling the movement of a throttle plate within a throttle body that operates to control the amount of air delivered to an internal combustion engine. The ETC driver (typically an electric motor) receives signals from the engine and/or the electronic control unit (ECU) of the vehicle directing the ETC to move the throttle plate to a degree dictated by the air requirements of the engine condition. It is also known that the throttle plate may sometimes become stuck or its movement inhibited by debris formed around the plate. For example, when an engine is running, the temperature of the engine and surrounding components can operate well above the ambient temperature. Once the engine is shut off (engine soak), the engine begins to cool until it is in equilibrium with the ambient temperature. In cold climates, the engine temperature can thus dip below freezing temperatures as it goes through engine soak. In this situation, moisture around the throttle plate can freeze and present a potential block to proper throttle movement once the engine is started again. Other matter such as coke from the combustion process or chemical contaminants in the air/fuel mixture can add to the obstruction causing the throttle plate to stick or bind.
When a stuck or binding condition is sensed, it is known in the art for the ETC to simply set throttle actuation faults directing the throttle blade to move to a slightly open position which allows only enough air to reach the engine for a “limp home” condition. If a stuck throttle in a near or fully open position occurs, the ETC system can reduce the available power to idle only or may completely disable the engine in some cases. In some cases where the obstruction could have been readily removed safely before the fault setting was made, the system nevertheless resorts to the fault setting rendering the vehicle inoperable or nearly inoperable instead of attempting to clear the obstruction.
There therefore exists a need for an ETC system and method directed at sensing potential or partly formed obstructions near the throttle plate in the key-on mode, while the engine is cranking and while the engine is running, and directed at initiating remedial measures to clear the obstruction before resorting to the fault setting.